Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune- mediated predominantly motor disorder that accounts for about 20% of apparently undiagnosed neuropathies. Both humoral and cellular immune mechanisms are implicated in the etiology, but their relative contribution remains unclear. Most currently available immunomodulating treatments for CIDP can produce major side effects, and 30-40% of patients show an inadequate clinical response. Intravenous human immune globulin (IVIG) therapy has recently been employed with good results and minimal side effects in several immune-mediated disorders associated with disordered humoral and cell-mediated immunity, including in uncontrolled studies in CIDP. We will undertake a multicenter double- blind, placebo-controlled treatment trial in CIDP to determine whether therapy with IVIG in previously untreated patients produces greater improvement than placebo (5% human albumin) over 6 weeks. A total of 100 CIDP patients, meeting strict inclusion and exclusion criteria, will be enrolled in this study from 20 participating centers over an 18 month period. The primary outcome measure will be manual muscle strength as determined by an expanded MRC grading scale. Secondary outcome measures will include handgrip strength, forced vital capacity, timed functional tasks, a functional disability scale, and electrophysiological data. Careful monitoring of side effects and treatment failures by local center personnel and Centeon will ensure patient safety. Effectiveness of therapy will be evaluated using repeated measures analysis of variance stratifying for treatment center. Sample sizes have been derived such that the proposed study has sufficient power to detect a reasonable treatment effect. Progress in the study: The study has to date enrolled a total of 45 patients. Future plans for the study: Data analysis will be undertaken when enrollment of the 100 patients is completed.